Apparatus for controlling the coating of selected surfaces of an article of manufacture

ABSTRACT

Apparatus for masking selected surfaces of an article of manufacture, for instance restricted entrances and beyond of stator cores, while other selected surfaces are being coated with coating material. A member having extensions formed with enlarged free ends disposed beyond the restricted entrances in spaced relationship therewith is detachably mounted in heat exchange relation on a cooling jacket sealed at a number of locations. During the coating of the other selected surfaces, fluid is supplied in the spaces between the member and the selected article surfaces to prevent material buildup on the article. Coolant is circulated through the jacket to maintain temperature of certain regions of the member and jacket below the melting temperature of the coating material. In this way, the selected surfaces of the article are efficiently and effectively masked while at the same time certain components, such as the member having the extensions, may be rapidly disassembled and reassembled without disturbing the sealed nature of the jacket.

iliteei States atent Pieper et al.

APPARATUS FOR CONTROLLING THE COATING 0F SELECTED SURFACES OF AN ARTICLE OF MANUFACTURE Louis W. Pieper; Robert 0. Kerr, both of Fort Wayne, Ind.

Inventors:

Assignee: General Electric Company Filed: Nov. 21, 1969 Appl No.: 878,624

Int. Cl i ..B05b 15/04 Field of Search ..1 18/301, 69, 504,505, 63

References Cited UNITED STATES PATENTS 3/1967 Smith ..1l8/301X 2/1968 Mommsen ..l18/301X COOLANT Feb, 1, 1972 [57] ABSTRACT Apparatus for masking selected surfaces of an article of manufacture, for instance restricted entrances and beyond of stator cores, while other selected surfaces are being coated with coating material. A member having extensions formed with enlarged free ends disposed beyond the restricted entrances in spaced relationship therewith is detachably mounted in heat exchange relation on a cooling jacket sealed at a number of locations. During the coating of the other selected surfaces, fluid is supplied in the spaces between the member and the selected article surfaces to prevent material buildup on the article. Coolant is circulated through the jacket to maintain temperature of certain regions of the member and jacket below the melting temperature of the coating material. In this way, the selected surfaces of the article are efficiently and effectively masked while at the same time certain components, such as the member having the extensions, may be rapidly disassembled and reassembled without disturbing the sealed nature of the jacket.

2 Claims, 3 Drawing Figures PMENTED FEB I 872 INVENTORSZ LOUIS w. PIEPER. ROBERT o KERR,

ATTORNEY COOLANT APPARATUS FOR CONTROLLING THE COATING OF SELECTED SURFACES OF AN ARTICLE OF MANUFACTURE CROSS-REFERENCE TO RELATED APPLICATION This is a division of the copending U.S. application Ser. No. 7l0,103 filed Mar.4, 1968.

BACKGROUND OF THE INVENTION The present invention relates to an improved apparatus for controlling the coating of selected surfaces of an article of manufacture. In particular, the invention relates to improved apparatus especially adapted for masking selected surfaces of magnetic cores to prevent coating material buildup at those locations while other selected surfaces of the cores are being coated.

Certain articles of manufacture are formed with at least one passageway extending entirely through the article, the passageway being in open communication with a periphery of the article through a restricted entrance. Protective coatings are formed on preselected surfaces while other selected surfaces are maintained substantially free of the coatings for one reason or another. Taking dynamoelectric machine stator and rotor cores by way of illustration, it is becoming increasingly common to form a bonded or a fused protective ground electrical insulation coating, normally referred to as an integral insulation" coating, adhering to passageway walls of the cores, e.g., winding-accommodating slot surfaces, and to mask other surfaces. U.S. Pat. Nos. 3,355,309 and 3,355,310 issued Nov. 28, 1967 are representative of these practices. In some core designs the restricted entrances to the slots are formed by opposed surfaces of enlarged tooth section lips which have concavely curved wall surfaces disposed between the restricted entrance and the sidewalls of the associated slot. In some instances, it is quite desirable not only to maintain certain peripheries of the cores and slot entrances generally free of coating material by masking these regions, but also to keep at least a part of the somewhat inaccessible concavely curved wall surfaces, mentioned above, generally free of material buildup which before the present invention was difficult, yet quite desirable to accomplish.

It has been proposed in masking selected surfaces while applying fusible coating material on the other surfaces to employ masking apparatus which utilizes two different and separate fluid systems, such as air for the one system and a coolant in the form of a refrigerated circulating liquid such as water. It is quite desirable to satisfactorily maintain the component parts of the masking apparatus, which might come into contact with the fusible coating material during the application of the coating, below the temperature at which the coating material fuses. It is also desirable to construct such apparatus such that a minimum number of parts may be rapidly changed in the apparatus to accommodate articles of different sizes and configurations without disturbing various seals associated with the circulating liquid coolant system so that the chance of introducing leakage at the sealed locations of the system is also minimized, if not entirely eliminated. These desirable features should be attained economically yet efficiently at as low a cost as possible by an arrangement capable of use in mass production manufacture of the articles involved.

SUMMARY OF THE INVENTION It is therefore a principal object of the invention to provide an improved apparatus for controlling the coating of selected surfaces of an article of manufacture.

it is a more specific object to provide an improved apparatus, especially adapted for masking selected surfaces of magnetic cores, which tends to prevent material buildup thereon while other selected surfaces are being coated and which overcomes at least some of the problems and provides the desirable features mentioned above.

It is another specific object of the invention to provide improved apparatus, capable of use with a number of magnetic cores of different sizes and configurations, which is economical to construct, yet can effectively mask certain hard to mask or somewhat inaccessible surfaces of the article while other surfaces are being coated.

It is another specific object of the present invention to provide improved apparatus incorporating at least two fluid systems which can be rapidly and efficiently disassembled and reassembled with the same or certain other component parts without disturbing seals in one of the systems.

In carrying out the objects in one form, we provide an improved yet economical apparatus for masking selected surfaces of an article of manufacture; for example, a peripheral surface of a stator core, opposed surfaces forming restricted entrances to associated passageways extending entirely through the article, and surfaces of the passageways disposed immediately next to or behind the opposed surfaces, while other selected surfaces are being coated with coating material. The apparatus includes a structure having a cooling jacket sealed at a number of locations for receiving circulating coolant, and having a member detachably mounted in heat exchange relation with regard to the cooling jacket to permit removal of the member from the structure as desired and control of the temperature of certain regions of the member. This is particularly effective in maintaining the temperature of regions of the member exposed to coating material below the melting temperature of the material when it is fusible in nature, such as powdered epoxy resin.

At least one, and in connection with the stator core of the exemplitication, a number of angularly spaced-apart extensions or projections are removably carried by the member, the projections extending through the restricted entrances in spaced and adjacent relation to the opposed entrance surfaces. The free ends of the projections include enlarged sections adapted to be positioned in spaced and adjacent relation with respect to the surfaces disposed behind the restricted entrances. By supplying fluid to the spaces which flows along the walls of the member including the projections having the enlarged sections while the other selected article surfaces are being coated, coating material buildup on the selected surfaces of the article may be effectively and efficiently prevented.

Among other beneficial features, the foregoing arrangement also permits rapid and efficient disassembly and reassembly of the member as well as the individual projections relative to the cooling jacket without disturbing the sealed nature of the jacket to reduce, if not entirely eliminate, the chance of introducing leaks during disassembly at the sealed locations. This permits the use of the same or a number of different members and projections which may vary in size and configuration as dictated by the particular article involved employing the same cooling jacket and other component parts of the apparatus to provide versatility and economy in its use.

The subject matter which we regard as our invention is set forth in the appended claims. The invention itself, however, together with further objects and advantages thereof may be better understood by referring to the following more detailed description taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a cross-sectional view of improved apparatus in connection with the masking of selected surfaces while applying powder resin coating material onto desired preheated coilaccommodating passageway or slot surfaces of a dynamoelectric machine stator core to illustrate the preferred form of the present invention;

FIG. 2 is a view taken along line 2-2 in FIG. 1 to show additional details; and

FIG. 3 is an enlarged view of a portion of the apparatus and core exemplification shown in FIGS. 1 and 2 after powder resin coating material has been applied and coalesced into an adherent integral insulation coating on the desired locations of the slot surfaces.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawing in more detail, the preferred embodiment of the invention is illustrated by way of exemplification in connection with an article of manufacture in the form of a laminated core of the type more fully described in the A. A. Brammerlo US. Pat. No. 3,235,762. The core may be built from a number of conventionally held together laminations in stacked relation, annular yoke section 11 and angularly spaced-apart tooth sections 12 together defining coil-accommodating passageways in the form of slots 13. The tooth sections each terminate at the free ends in enlarged lips 14 having curved peripheral surfaces 16 which together form an axial bore adapted to receive a rotor (not shown). Opposed entrance surfaces l7, 18 of adjacent tooth section lips define restricted slot entrances communicating between the bore 16 and slots 13 in the usual way, with concavely curved surfaces 19 disposed immediately next to the restricted entrances joining the sidewall surfaces of the slots to their associated slot entrances. Conventional slot wedges of the type shown in the Brammerlo patent and formed of insulating material are adapted to rest against concavely curved surfaces 19 to close the slot entrances in the finished core.

In the illustrated exemplification initially the core is preheated to a temperature above the fusing or melting point of the particular resin coating material in powdered form which will form the integral insulation coating bonded to the desired surfaces, such as slot surfaces 13 in the core exemplification. The phrase fusing or melting point as used herein denotes the temperature at which the powdered material flows, melts, and becomes sufficiently tacky to adhere to the selected heated core surfaces, the material also being sufficiently fluid to coalesce and form a continuous coating. The type of coating material may be suitably formulated for the particular application, such as those mentioned in the Bender et al. US. Pat. No. 3,355,309 and the F. C. Avila US. Pat. N0. 3,] 36,650 issued in the United States on June 9, I964.

The preheating of core 10 may be accomplished in any wellknown manner. For instance, induction heating may be utilized or a controlled amount of heat may be introduced into a conventional convection or infrared oven (not shown). After the temperature of the stator walls to be coated has been elevated above the melting point of the coating material the desired degree, but below the decomposition temperature of the material, the stator may be removed and transferred onto apparatus 20 which incorporates one form of the present invention.

It will be recognized that some methods of applying fusible coating material may not require a preheating step, such as those outlined in the Avila patent. However, in the illustrated embodiment, stator core 10 is in a suitably preheated'condition when it is placed onto apparatus 20. The exact preheat temperature for the article is dependent, of course, upon such factors as the material employed, the materials deterioration or decomposition temperature and gellation characteristics, as well as the rate of heat dissipation from the regions of the article being coated.

Considering now in more detail the illustrated embodiment of apparatus 20, it both supports and masks the selected surfaces of the core exemplification. It comprises a structure suitably supported for relative rotation with respect to generally opposed coating material or powder applying devices 21, 22 which, as shown, are similar in construction to those revealed in the Bender et al. patent previously mentioned and are disposed in pairs on each side of the core. In order to direct coating material toward the slots, slot edges at the side faces of the core, and the side faces themselves, each pair of devices on the same side of the core are located at different radii from the axis A" of the core. This ensures the desired spray pattern and coating coverage on the core. The structure has a cooling jacket 23 fabricated from rigid thermally conductive material such as steel, aluminum, or the like, capable of conducting heat toward coolant receiving chamber 24 fonned by annular outer wall 26 and axially separated sidewalls 27, 28.

A removable metallic member 30, having a plurality of replaceable blade extensions 31 corresponding in number and location to the entrances of slots 13, is detachably mounted in heat exchange relation with respect to wall 26 of jacket 23 and has a slip fit with the circumferential surface of jacket wall 26. 1n the illustrated embodiment, extensions 31 have base sections 32 generally rectangular in cross-sectional configuration received in suitably placed complementary axial channels 33 formed in the body region of member 30. Each end of member 30 and extensions 31 respectively include axial projections 34, 36 and 37, 38 accommodated under annular flange 39, of end plate 42 and radial section or flange 41 of jacket wall 28. With this arrangement, extension base sections 32 may readily be inserted into channels 33 before member 30 is assembled onto jacket wall 26, member 30 then being slid over wall 26 until projections 36, 38 enter beneath flange 41 into the relative assembled positions shown in FIG. 1.

To complete the assembly of the components, end plate 42 is placed with flange 39 overlapping projections 34, 37 and secured to the structure by any suitable means; e.g., plate 42 fitting onto the outer surface of hollow shaft 44 in axially spaced relation to jacket wall 27 and being secured in place by internally threaded nut or cap 46 which closes the end of axial passageway 47 of shaft 44. This procedure is reversed when member 30 and extensions 31 are being disassembled from the supporting structure.

It should be noted at this time from FIG. 1 that in the illustrated exemplification such assembly, disassembly, and reassembly of member 30 and extensions 31 may take place without disturbing the sealed nature of cooling jacket 23 or of the recirculation system for the fluid coolant passing through chamber 24. More specifically, as shown, coolant is introduced into sealed chamber 24 from a conventional heat exchanger (not shown) through a pipe and inlet 51 of a standard rotary coupler 52, into duct 53 formed by a longitudinal groove machined in the outer surface of hollow shaft 44 and the inner surface of sleeve 54 which encircles the shaft, and into the jacket chamber via radial opening 56. After the coolant circulates in the chamber and absorbs heat from the surrounding jacket walls for cooling purposes, it is discharged back to the heat exchanger through outlet opening 57 into duct 58, formed by another longitudinal groove in the outer surface of shaft 44 and the inner surface of sleeve 54, and finally through outlet 59 into pipe 61 for return to the heat exchanger where the temperature of the coolant is reduced the desired amount. An assumed direction of flow for the coolant is indicated by the arrows in FIG. 1. Jacket wall 27 is suitably sealed, as by a welded joint 62, to the outer surface of shaft 44 while radial wall 28 abuts against shoulder 63 provided on the periphery of sleeve 54 where it, too, is suitably sealed, as by weld 64.

Consequently, the seals between the jacket walls and the supporting sleeve 54 on the one side and shaft 44 on the other for chamber 24 will remain undisturbed whenever member 30 and its extensions 31 are changed for whatever reason relative to the other components to minimize the chance of introducing leaks at the seals into the closed coolant system.

In order to reduce the tendency of coating material buildup on opposed surfaces 17, 18 and concaved surfaces 19 in the core of the exemplification during the coating operation, the radially outermost sections or free ends of extensions 31 are formed with cross-sectional enlargements 66, and the sections connecting the enlargements to the base sections are somewhat undercut to produce spaces of predetermined widths between the peripheral walls of the extensions and adjacent core surfaces through which fluid, such as air, under low pressure, may be guided. During the coating operation fluid may be supplied to these spaces from a suitable low fluid pressure source (not shown,) for instance below 22 p.s.i., and through passageway 47 of hollow shaft 44 which may be connected through a standard rotary valve (not shown) to the source. AS indicated by the arrows, the fluid passes from passageway 47 into the radial space 67 formed between end plate 42 and jacket wall 27 via a number of radial holes 68.

The fluid then passes into axially extending holes 69 and grooves 71 provided in the body region at the common end thereof, the grooves being in open communication with the peripheral surface of member 30 intermediate extensions 31, best seen in HS. 2.

A restricted space 72, for instance in the neighborhood of 0.002 inch or 2 mils, is maintained between the core bore and the periphery of member 30 to permit positive flow from the individual grooves 71 into spaces 73 formed between the extensions 31 and adjacent surfaces of the core. A number of angularly spaced-apart protuberances 75, mounted next to a few extensions, firmly engage the inner tooth surfaces of the core at the bore, to hold the core on apparatus in the desired position. It has been found in actual practice that, in order to derive the best masking results with the illustrated embodiment, the widths of spaces 73, 74 are preferably in the range of 0.007 to 0.002 inch (7 to 20 mils), with a fluid flow pressure slightly above the pressure being supplied to material applying devices 21, 22 when such devices are employed. Generally speaking, in regard to the use of spaces having widths less than 7 mils and pressures below that for devices 21, 22, it has been observed that there is a tendency for material buildup and bridge the spaces. It has also been found that efficiency of the masking operation is improved by undercutting the extensions between the base and enlarged sections and curving the corners of the extensions to permit a smooth flow path for the fluid along the extension walls. Also to ensure an absence of coating material on the core surfaces for a radial distance indicated by numeral 76 in FIG. 3, that is, to a point beyond core surfaces 19, flat sidewalls of enlarged section 66 are provided in the vicinity of the termination of surfaces 19, the exact configuration of the enlarged section being a factor as to the total extent of masking attained.

By forming the enlarged sections with gradually diminishing cross-sectional transverse dimensions to produce converging walls, the fluid will flow along the periphery of the extensions, away from the slot surfaces to be coated and toward the respective centers of the slots to reduce the chance of interference by the flowing fluid with proper coating of the selected slot surfaces. In other words, by directing the fluid flow toward the terminations or tips of the enlarged sections, the fluid expands outwardly and becomes dissipated away from the slot surfaces being coated. It has also been discovered that with the illustrated configuration for the extensions, there is no need for polishing the exposed periphery of the extensions during their manufacture to achieve good masking functions. Rather, an inexpensive grinding operation is sufficient.

The illustrated manner in which apparatus 20 serves to mask selected surfaces of the core in the exemplification as other selected surfaces are being coated will now be considered in more detail. After the uncoated core has been preheated to the proper temperature, it is slid axially onto axial protuberances 75 of member 30, with extensions 31 being received within the slot entrances and associated slots of the core to produce the spaces 72, 73, and 74 previously discussed. The forward axial end of the core should be disposed in the neighborhood of the end wall of groove 71 while the other end of the core is in the vicinity of an end wall of extensions 31. The flow of the fluid is initiated through the hollow shaft and ultimately into spaces 72, 73, and 74 as relative rotation is imparted between material applying devices 21, 22 and the core. This may be accomplished by rotating the article supporting structure: shaft 44, sleeve 54, jacket 23, member 30 including the extensions, and plate 39, as well as the core mounted thereon as a unit.

As the coating is being applied to the selected surfaces of the core; e.g., core end surfaces, slot edges, and slot surfaces 13 in basically the way outlined in the previously mentioned Bender et al. patent, the inner peripheral surface of the core, opposed surfaces 17, 18 of the restricted entrances, and curved surfaces 19 will be effectively masked by member 30 including extensions 31 and the flow pattern already discussed in connection with the fluid, such as air. At the same time, the cooling fluid or coolant circulating through chamber 24 will serve to take heat away from the innermost regions of member 30 as well as exposed wall 28 of the jacket among other locations, to assist in maintaining certain exposed surfaces of apparatus 20 below the melting temperature of the coating material, thereby reducing the chance of material buildup on the exposed surface.

As the coating material is being deposited on the desired surfaces of the core, the heat energy emitted from the core walls causes the deposited material to melt, gel, and flow slightly, coalescing into a generally uniform, imperforate, and adherent integral insulation coating 77. Once the core has been coated, the flow of coating material and fluid through member 30, and the relative rotation, may all be terminated and the coated core then removed from apparatus 20. However, the coolant may be continuously recirculated through chamber 24 even after cessation of the coating operation.

If articles of other sizes and configurations, for example, inside-out motor rotor cores, are to be coated, or in the rare event that extensions 31 become unduly wom from use and should be replaced, either extensions 31 individually or member 30, or both may be changed by merely dismantling these parts from the other components of apparatus 20 and substituting the desired parts. For example, for cores having different bore diameters, axial lengths, and slot entrance sizes, it may be desirable to replace member 30 including extensions 31 with parts of the proper shapes and sizes. The axial length of grooves 71 in the new member 30 should conform generally to the axial length of the core. The internal size and shape of member 30 would still, however, be similar to the parts being replaced and complement the jacket walls in the way already discussed. Thus, economy in labor and parts, efficiency, and versatility in use to effectively mask selected surfaces of articles while coating other selected surfaces are the primary advantages achieved by the present invention. Although the invention is particularly effective when used with stator cores, as previously suggested, it may be employed in connection with other articles of manufacture having passageway entrances at peripheral surfaces.

It should be apparent to those skilled in the art that while we have shown and described what at present is considered to be the preferred embodiment of our invention in accordance with the patent statutes, changes may be made in the disclosed embodiment without actually departing from the true spirit and scope of this invention, and we therefore intend to cover in the following claims all such equivalent variations as fall within the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for masking selected surfaces of an article of manufacture, having a plurality of passageways therethrough in communication with a peripheral surface through an entrance, while other selected surfaces are being coated and for masking additional selected surfaces disposed immediately next to the entrance surfaces which form a restricted entrance, the apparatus comprising a structure having a cooling jacket permanently sealed at a number of locations and adapted to receive a coolant; means for supplying a coolant to the cooling jacket, said means being permanently secured with the cooling jacket; a member positioned on the structure ad jacent the cooling jacket having a preselected wall to be disposed in spaced and adjacent relation with a selected peripheral surface of the article, and having a plurality of projections adapted to extend into an associated passageway entrance in spaced and adjacent relation with selected surfaces forming the entrance, each projection including an enlarged section adapted to be disposed in spaced relation adjacent the additional selected surfaces for guiding flow of fluid past the additional selected surfaces to prevent the application of a coating thereon; means detachably mounting the member in heat transfer relation with the cooling jacket to permit removal of the member from the cooling jacket without ture of the predetermined regions of the member is being controlled.

2. The apparatus of claim 1 in which the member has a number of spaced-apart protuberances for supporting the artisic in spaced and adjacent relation with respect to the preselected wall of the member 

1. Apparatus for masking selected surfaces of an article of manufacture, having a plurality of passageways therethrough in communication with a peripheral surface through an entrance, while other selected surfaces are being coated and for masking additional selected surfaces disposed immediately next to the entrance surfaces which form a restricted entrance, the apparatus comprising a structure having a cooling jacket permanently sealed at a number of locations and adapted to receive a coolant; means for supplying a coolant to the cooling jacket, said means being permanently secured with the cooling jacket; a member positioned on the structure adjacent the cooling jacket having a preselected wall to be disposed in spaced and adjacent relation with a selected peripheral surface of the article, and having a plurality of projections adapted to extend into an associated passageway entrance in spaced and adjacent relation with selected surfaces forming the entrance, each projection including an enlarged section adapted to be disposed in spaced relation adjacent the additional selected surfaces for guiding flow of fluid past the additional selected surfaces to prevent the application of a coating thereon; means detachably mounting the member in heat transfer relation with the cooling jacket to permit removal of the member from the cooling jacket without disturbing the sealed locations of the cooling jacket thereby reducing the chance of introducing leaks at the sealed locations, and to allow temperature control of predetermined regions of the member; and means for supplying a flow of fluid to the spaces between the member including the projections and the selected surfaces of the article for guiding fluid flow therethrough to present the coating thereof as the temperature of the predetermined regions of the member is being controlled.
 2. The apparatus of claim 1 in which the member has a number of spaced-apart protuberances for supporting the article in spaced and adjacent relation with respect to the preselected wall of the member. 